Sealed circumferential joint for fuel tanks



extreme tightness and high pressures be achieved in order of withstanding extreme'tensile'stresses, and it cannot i distinguished from acontinuous annular-connector memher.

I 2,329,910 v V 1 SEALED CIRCUMF RENTIAL JOINT non FUEL j 5 TANKS V a v Gerald A. Miller, Northridge, Califl, assignor to Royal Jet, Inc., Alhambra, Calif., accorporation of California Q I Application March 4,1955, Serial No;492,223 1o 14 Claims. or. 285- 370 'This invention relates to a circumferential joint con 15 1 structiomand more particularly to a means and method for sealing'l'y joining adjacent skin sections of a jettisonablefuel tank for aircraft. a Jettisonable fuel tanks fonaircraft are frequently, 'con structed in a plurality of components whichfma'y be stacked or nested together during shipment for the purpose of conserving shipping and storage space," the tanks then being assembled at their destinationand as required a for the military operation being carried out. It wilfbe apparent that when the various skin section components of each jettisonable fuel tank are assembled together, some means must be provided to prevent leakage of fuel through the joints. The problem of constructing ade- 7 simple and inexpensive manner, has hereto'f ejbeen. aigreat problem to jettisonable fuel tank man nr'ers. Oneimportant reason for the problem has been; that the pressure which should be placed upon a seal toefiectoptimum sealing may be very diiferent from the pressure which should be applied to the actual connectorfmembers in order to prevent their failure and breakageunder the extremevibratory and other stresses. encountered :when the tanks arepcarried beneath the wings of military aircraft. j

To amplify upon the above it will bennderstood that when metallic joint components are screwed or other- 4 wise secured together to form a joint it is desired that that the joint will be as strong as po ssible 'and will be able to withstand the forces to which it may be subjected; In particular, it is desired that each bolt' in the jointbetensioned, due, to turning'of the associatedfnut, until the tensile stress in the bolt is as great orgreater than the greatest stress to which the, bolt will be subjected 7 during flight conditions. When such a tension is" achieved and maintained, the bolt cannot fail by" tension since in order to be' tightened as indicated itmustbe capable fail by fatigue since fluctuations in the load will not affect the tensile forces in the I bolt. However, it has been found that when such highstresses are applied in con ve'n'tionaljoints, any O-ring-or similar seal. along the circular line of abutment between the skinconiponents may be crushed and deformed to'such; an; "extentthat its sealing usefulness is impaired. Accordingly ti al means. ha lonsb soug t o i g 3h? .8. pressure independent, ofthe joint pressure yet which simple and economical and is internal instead ofig cternal c so as; not to createundesirable air drag. This'is p ar ticularly true with relation to circumferential joints-em ploying aplu al y f: ar at pas dsv ne o ,b a k s,

in; view of ;the above problems characteristic of faireumferentialjoints for jettisonable fuel tanks, it is an object of the. present intention, to provide a circumfen entia-l-joint in which the sealing pressure is independent skin sections of a JQttisbnable wing tank for aircraft, and

In the drawing:

tional' view, on line 2+2 ofFigure l, of the'fjoin t be-.

. a nose section 10, center section 11 Formed between the adjacent cylindricalc end portions of "centjersection 11 and. each of the nose and tail'secan annular seal support member 15, an annular s inwardly from the line of abutment I tank sections; The'brackets 14: extend longitudinally to Whicha circumferential joint is-subjectedin servi respective skin sections 11 andllZ u i s senat iofla f el: a k

' drical bodyrconcentric'with theitank axis "and spaced wardl-y a substantial distance. from the abutment lin r diall x nd;

' c I PatentedA r f 3 Another o j ct is to p ovide a simpl ndfcc nennc means and methodffor joining 'in endwiseqabutment the which employs only a relat ively small number of arena spaced connector brackets yet is'-' stro ng and 'provi fuel-tight seal. 1 to r o 1 f;

These and other objects and advantages of the in'ven; tion will be more fullyset forth int'the following specific-a '7 tion and claims considered in connection with the attached drawing to which they relate. a a I Figure-fl is a longitudinal elevational view showing-Jan I assembledfuel tanlglthe main circumferential joints 1 of which are constructed in accordance with the present invention; 7 Figure Z'is an enlarged fragmentary longitudinal sectween the center-and tail sectionsdf-the ftankvillustrated in Figure 1, showing the'jointbefore application of sealingpressure; f Figure 3tcorresponds to'Eigure 2 hutshows thejposi- V tions of the parts after application of sealing pressure; Figure 4 is a transverseffragmentary sectional vie'w, on line 4-4'of Figure 1,, illustrating the means for apply ing sealing pressure, but before application of such pres. sure; and a t p V j Figure 5 is, a view of the meansishown' in Figtirei,

taken from station 55 in Figure'4.

Referring no t e d w ng; and P t lar y to Figure 1, there is illustrated afjettisonble-fuel tank fer 7 aircraft comprising a thin-walled aluminumskin having:

and tail section 12."

tions 10 and 12' is a circumferential joint constructed in. accordancewithithepresent invention; The circnni ferential joints being identical, only the one between:

The connector-brackets 14 maytake the form of gen erallywing-shaped: metal-meinbers having channels ,1 formed exteriorly at their central portions, thellowe'r walls of the, channels being spaced a'suhs'tantial distance 19' between-"the the tank and 'are'mounted in arcuately spaced relationship V sufficient brackets being employed to'withstand' the stresses" Seal support member 15- is formed of mani aer relatively: rigid; material, and comprises. a general; n-

The cy lindrical hody' curves outwardly at. its ends to is l i an l' fihs p r s f fiis spaced inwardly from the s sunuo,rt vmen ber extends I 7 inch are also ckets 14, andmay be either d therefrom as formed of rubber or .othr suitable astic material,- and is shown in d state in Figure 2, 'andin its rringffirst-to Figure 2,

ay be seen to comthe base or web of er diameter just slightly less abutted tank sections 11 ann'elbody 30 extend, gen- 7 and are integral with 7 support member in flanges 26.1 Provided 'on oose contact; with the: skin xtending sharp 7 ,Seal member 16 is elastomeric 'or resilientp its natural or undeforme deformed 'state in Figure 3.- Refe the undefo'rmed seal member 16 m prise a body of chan the' channel having an out than the inner diameter ofth and 12; The flangesofrthe-ch erallytoward the the beads'31 which seat on distance inwardly fromits 'ca beads 31, and coming int sections, 'are a plurality o edged sealing lips or edges 32. The seal 'pressu'refmeans 1 illustrative ofthe presently preferred embodiments o center ofthe t Y inwardly of the line ,ofabutment betweensaid end 'po f outwardly e L tions, a cylindrical seal support ring mounted in's V chann'elsand having radially outiq'vardly ext 'ng am 7 comprises an annular strap orband 36, preferably formed offlexible m While the particular method-and apparatus her shown and disclosed indetail are fully capable of attain ing theobjects and providing the advantages 'hereinbe fore stated, it is to be understood thatthey are 'merel invention and that no limitations are intended to th de tails of construction or design herein shown otheritha as defined in the appended claims. j f

I claim: 1

1 r 1.' A sealed circumferential joint between th cylindrical 'end portions'of jettisonable fuel'tank skin tions, which comprises a plurality .of longitudinally: tending arcuately spaced; connector brackets secured tween said'endportions' andinternally" ofsaid tank, sat brackets having transverse outer channels therein 'radiall flanges, antelastomeric .seale ment ,m outwardly of said support; ring betwee said seal element having :an inner {groove portion andradially outwardly extending lips dtbetween andin abutment with 12 and the baseiof seal channel e 2. The ends of strap 36' .37 (Figures {and 5)to fit around" uckle 38 h'aving'a nut portion" 38 is external to the fuel tank, being which is, initially mounte the skin secti'ons' 11' and portion Silas sho are looped over at the endjpo'rtions 39. 'Turnbuckle "tion' end portions, and meansto reduce the diame e'ban'd mounted between sai portions, a flexibl V line of abutment between said kin portion and said said band to force said seal centerportion againstfsaid;

- seal support ringand effect 'camnung distortion offsaid erally' rectangular slot 41 formed be Hand 12 as shown in Figure 5. It is uckle 38 is the only component ch is external to the fuel tank, a

e or drag created by-the seal turnbuckle 38' provided in a gen tween skin sections emphasized that the turnb of the s'ealingmeans Whi so that the wind resistanc means is negligible; and seal means '16 is a damage to the seala According to' the ring 16 is first mounted in' and the seal pressure me around so that the parts- 2. The tank-skin-sectio endwise abutment by insertin 36 as illnstrated'. Thereafter, in position through use of'bolts priorto theassembly ofnose section an operator may 'ge It isjpointed out that the tightening of a torque determined solely by the seal element toforce said hp "against thef're'sp'ectiv Mountedbetween the stantially confined to the interior of the-1 a'nk -plate'42 adapted to prevent s" the itrunbuckle. is operated.

method for the" inven the seal support channel 15,

17 is mounted looselythete have the form shown in Pigure' v 'and' 12 are then placed'in g them over lips 32 and band. the brackets 14 are mounted 2 1 and nuts 24 and 10 with the center t inside the tank 'to" section ll s'o that tighten the nuts; the nuts 24 is to sectionsI 2. An internal couplingfo'rj Y tank sections together with; the parts of plingcomprising circumferential; by spaced U connectors inside said tank holding 'said sections'm ting relation, an outwar'dlytopening channeledb nd circling said connectors,.anoutwardlychanneled V elastomer supported in said tbarid aiidfsub ntially fillin theisame, andtmeanst for compressing'lo 1" tion of said rin'grof elastomer against ebotto walls of-sa id channeled band ther e byiforcin fa r elastomer fto either side ithereofradiallyf outward fluid-tight engagement'with the interior wallso said tan sections; i

3. An internalcouphng as defined. 2 w said means for compressing said ring f l to eludes manually adjustable -.m' eans1'PQie throughanjopeningin saidsthin lled tank se and the desired tensile irements of the joint ly independent of the t 'r qu jbolts 21,'being entire stresses on-the necessity of sealing theline of abutment.

I It is then merely necessary tank to the turnbuckle nut ends 37; of band 36 'toge thereof.- The channel porti flattened against seal support mem e 3. Thetflanges o t fonan operator, on

3? and draw the looped ecrease th e diameter on 30 ofseal means16 is'thus ber 1 5 to the position f the channel portion twardly so as to force beads 31 the seal, support. Asfthebeads flanges 26, the sealing lips 32 are; dly against the respective skin sec-;

and provide efiective fluidf age into the regionof abutd outthat the outer'ones of, outwardly between cam flanges 26" this outward 553 tank sections and in an area 7 shown in Figur 30 then tend to spread on 7 against cam flanges 2 31';press against cam forced radially-outwar tions 11 andv 12 (Figure 3) tight seals preventing any 1e ment line 19." It is pointe lips 32 curl radially and the associated'skinsections, and that curling is desirable in that any fluid pressure acting i against these lips willoperate to increase the effectiveness of theseal. 1

In' the described man sure between lips 32 and s mined by the seal dependent of bolts pressure may therefore and thabp t' strongest joint,

1,6. In an internal coupling to outwardlybey'ond the opp "compressed radially inward, ag

p r W p thereabounanannu thout danger ofundesirable-iilteraction. in'saidbhannel'h: n as 4. An internal coupling ed 1 2 turnbucklemeans for adjusting he tension forgcompressing; said ring ofelastomen 1 5. An internal'coupling s; defined said-turnbuckle'means over iesjsaid ri, is accessible for adjustment-from, ap'o tern I between the lateral sea edges of said elastomer ring; 3 1 r'je t'tisonab fuel skin sections, an elastomeric 'sealihgoring'having an web 'and pair s of radialtfla es projectinginwar edges of'said web, said outw J ingythin-edged lips adapted;

fluid-tight sealing engagem I edges of abutting fuel Zta walls ofia'ring provided wi a nelthereabout. p

radially'outwardlyinto'se nt wr "the bottom of said tion and outwardly projecting sealing lip means along its lateral edges positioned closely beside said channel side walls with their sealing edges adapted to lie closely adjacent the interior surfaces of said shell members, and contractible hoopmeans operable upon being contracted against the bulging central portion of said elastomeric member to compress the same into said channel thereby forcing said sealing lips into fluid tight sealing engagement with the interior'surfaces of said shell walls.

8. A fluid tight joint structure as defined in claim 7 wherein said hoop means includes a turnbuckle operable when turned in one direction to expand said hoop and,

when turned in the opposite direction, being elfective to contract said hoop.

9. A fluid tight joint structure as defined in claim 8 wherein all portions of said hoop means are sealed from the interior of said shell members by said elastomeric ring when the latter is compressed and sealed against the interior surface of the shell members.

10. A sealing ring structure adapted for use interiorly of tubular members and operable for expansion outwardly into sealing engagement with the interior surface of such tubular members, said structure comprising a strong ring having an outwardly facing channel thereabout, an elastomeric ring seated therein having an outwardly bulging central portion bordered by radial lip means closely adjacent the side walls of said channel, and contractible hoop means embracing said bulging central portion operable when contracted to compress the bulge against the channel and force said lips to expand outwardly from either side thereof thereby forming a seal with the juxtaposed interior surface of a surrounding tubular member. 7

11. A sealing ring structure as defined in claim 10 wherein said contractible hoop means includes means for contracting the same while in sealing position interiorly of a tubular member.

12. A sealing ring structure as defined in claim 10 wherein the lateral sealing portions of said elastomeric ring each have a plurality of continuous sealing lips facing radially'outwardly to either side of said contractible hoop means. 1

, 13. A sealing ring structure as defined in claim 10 in combination with the interior abutting edges of two thin-walled shell sections of an aerodynamically contoured structure, and wherein said elastomeric ring is disposed to bridge and form a fluid-tight seal on the in terior side of said abutting shell sections.

14. A sealing ring structure as defined in claim 13 including rigid tie members interconnecting said shell sections transversely of said sealing ring structure'interiorly of said aerodynamically contoured structure.

References Cited in the file of this patent V UNITED STATES PATENTS 1,607,943 Carson Nov. 23, 1926. 1,788,845 Reynolds Ian. 13, 1931 2,209,235 Nathan July 23, 1940 2,214,177 Raybould Sept. 10, 1940 2,686,609 Fletcher Aug. 17, 1954 FOREIGN PATENTS I 321,563 Italy Oct. 9, 1934 

